Technical placement of residual valve with respect to placement of pressure activated brake light switch?

Is it acceptable to have a pressure activated brake light switch between your master cylinder and a residual valve?

I'm pretty sure you might have problems if you had the brake light switch plumbed between the residual valve and the brake cylinder/s

 

That sounds like the correct place to put it to me.

 

The pressure switch needs a lot more pressure than the residual valve will hold, to activate it.